Normal air diffusion reduces tire pressure over time. The natural state of tires is under inflated. Accordingly, drivers must repeatedly act to maintain tire pressures or they will see reduced fuel economy, tire life and reduced vehicle braking and handling performance. Tire Pressure Monitoring Systems have been proposed to warn drivers when tire pressure is significantly low. Such systems, however, remain dependent upon the driver taking remedial action when warned to re-inflate a tire to recommended pressure. It is desirable, therefore, to incorporate an air maintenance feature within a tire that will re-inflate the tire in order to compensate for normal air diffusion over time without the need for driver intervention.
U.S. Pat. No. 8,042,586 discloses a self-inflating tire assembly that includes an air tube mounted within a tire sidewall groove. The air tube is in contacting engagement with opposite angled groove surfaces surrounding the air tube. A segment of the air tube is flattened from an expanded diameter to a flat diameter by bending and compression of the groove in a rolling tire footprint to force air evacuated from the flattened segment along a tube air passageway. The sidewall groove extends into an annular, axially extending, sidewall surface such as an axially oriented surface of a tire chafer protrusion located in non-contacting relationship with the rim.
U.S. Patent Publication No. 2013/0160928 discloses a method of forming an air passageway in a an air maintenance tire carcass includes: embedding an elongate strip within a pre-cured flexible tire component of a pre-cured tire carcass, the elongate strip extending in a longitudinal direction between an air inlet cavity and an air outlet cavity in the flexible tire component; curing the pre-cured tire carcass including the flexible tire component; extracting the elongate strip longitudinally end-to-end from occupancy within the flexible tire component; and defining an air passageway in the flexible component by the space previously occupied by the withdrawn elongate strip. A free end portion of the strip is accessible at either the air inlet cavity or the air outlet cavity, and the elongate strip may be extracted from either the air inlet cavity or the air outlet cavity by a tensile withdrawal force applied to the elongate strip free end.